Plate type heat exchanger



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PLATE TYPE HEAT EXCHANGER Filed Oct. 16, 1962 ll Sheets-Sheet 10 llil WM j I 91W HHM I! f ON go d O 28m Q O Q 0 0 o O 360:1. l O O LT O Q l O O O O O G /l O O i O I o 240 T mi O 284 307i fg gli: O O O Q O 35@ O g 2a@ O 926- C Q O o O 0 O g Og 360e O O O L 0 32ag Q g Zai 3 0 G o g 0 TO l 'HMH 1 Q'j/O a /7 /f INVWORS'Q 1%. o n ams 41N s l/ BY/ cha/"d /f/eyser 522g. 25o ffy/el /e//f A TTORNE YS June 149 T96 J. H. DAvlDs ETAL PLATE TYPE HEAT EXCHANGER Filed Oct. 16, 1962 l1 Sheets-Sheet 1l trnw, /274 \\w (4 9 275-/ l V NTOR c/om Hams Day/d6 A TTORNE YS United States Patent O 3,255,8l7 PLATE TYPE HEAT EXCHANGER .lohn Hans Davids, Beloit, and Richard lF. Keyser, Clinton, Wis., assignors to Desalinaton Plants (Developers of Zarchin Process) Limited, Tel Aviv, llsrael, a limited company of Israel Filed Oct. 16, i962, Ser. No. 230,838 24 Claims. (Cl. 165-166) This invention relates to iluid heat exchange lassemblies and is more particularly directed to new and improved uid heat exchange method and means employing a pluralrlity of horizontally stacked or nested heat exchange p ates.

Heretofore, diiculty has been encountered in the design of heat exchange assemblies employing a plurality lof stacked or nested and horizontally disposed heat exchange plates of thin cross-sectional dimension. One of the basic problems in such design is that of providing a plate support assembly for the plurality of horizontally stacked plates which will prevent mis-alignment, translation and slippage of the plates during operation of the heat exchange assembly. This problem becomes particularly critical in heat exchange assemblies wherein 'a large number of such plates of thin cross-sectional dimension are to be horizontally stacked, for example, when -other critical design parameters of the heat exchange assembly are such as to require a large number of plates to be so stacked.

Another problem associated with the design of such heat exchange assemblies is that of providing means for 'hermetically sealing the assembly to prevent leakage of tluid during operation. In particular, means must be provided for adequately preventing -outward extrusion of the gaskets employed in spacing the plates to dene the fluid flow channels between plates an-d to seal heat exchange plates. Porting of the plates and gaskets in the design of a plurality of flow paths through the heat exchange assembly presents additional problems of sealing because the pressure of the fluid flowing into, and from, the lluid flow channel delined by adjacent heat exchange plates has a tendency to force the fluid flow inlet and outlet port dening portions of the gaskets from between the plates into the port area thereby permitting leakage between fluid ilow channels and possible mixture of the uids tlowing in heat exchange relation through adjacent channels.

Still another problem associated with the design of such heat exchange assemblies is that of controlling the fluid ilow into the fluid flow channels between adjacent heat exchange plates to minimize the effects of pressure surges at the inlet ports of the channels so that substantially uniform distribution f the fluid occurs inthe channel, whereby the heat exchange etiect of the system may be enhanced. In addition, pressure surges adjacent the outlet ports of the channel need to minimize by the provision of means for controlling fluid llow from the channels between adjacent heat exchange plates.

By employment of the present invention, the problems and diiculties of the prior art are substantially overcome by the provision of a heat exchange assembly for horizontally stacked heat exchange plates of thin cross-sectional dimension including a new and improved heat exchange plate support assembly, having means for aligning and strengthening the heat exchange assembly, means for hermetically sealing the heat exchange assembly and means for controlling distribution of fluid flowing between pre-selected channels in the heat exchange assembly.

It is, therefore, an object of the present invention to provide a new and improved heat exchange plate support assembly.

It is another object of the present invention to provide a heat exchange plate support'assembly for horizontally stacked or nested heat exchange plates.

It is another object of the present invention to provide a heat exchange plate support assembly for horizontally stacked or nested heat exchange plates which are Stacked or nested in a large number. v

A further object of the present invention is to provide a heat exchange plate `support assembly for horizontally stacked or nested heat exchange plates of thin cross-sectional dimension.

Still another object of the present invention is to provide a heat exchange support assembly for a three iiuid ow heat exchange system employing horizontally stacked or nested heat exchange plates of thin cross-sectional dimension.

A still further object of the present invention is to provide a heat exchange plate support assembly for horizontally stacked or nested heat exchange plates including means for aligning and strengthening the plates in the assembly.

A still further object Iof the present invention is to provide a heat exchange plate support assembly for horizontally stacked or nested heat exchange plates employing means for facilitating stacking of the heat exchange plates in the assembly.

Another object of the present invention is to provide a heat exchange assembly employing horizontally stacked or nested heat exchange plates of thin cross-sectional dimension.

Still another object of the present invention is to provide a heat exchange assembly of horizontally stacked or nested heat exchange plates employing a new and improved support assembly for the plates.

Another object of the present invention is to provide a heat exchange assembly for horizontally stacked or nested heat exchange plates including a heat exchange plate support assembly having means for distributing the pressure applied to the support -assembly during stacking of the heat exchange plates in the support assembly to form the heat exchange assembly.

A further object of the present invention is to provide a heat exchange assembly of horizontally stacked or nested heat exchange plates employing means for controlling the distribution of heat exchange fluid flowing into and from channels defined by adjacent heat exchange plates.

A still further object of the present invention is to provide a heat exchange assembly of horizontally stacked or nested heat exchange plates including means for hermeticallysealing the assembly which are carried by the heat exchange plates.

Another object of the present invention is to provide a heat exchange assembly of horizontally stacked or nested heat exchange plates employing means for tapping gaskets which are utilized to seal fluid flow channels between adjacent plates to prevent extrusion of the gaskets by pressure applied thereto by lluid owing through the said channels during operation of the heat exchange assembly.

Still another object of the present invention is to provide a heat exchange assembly of horizontally stacked or nested heat exchange plates including means for supporting said heat exchange plates in said stacked relation to prevent contact between adjacent plates which would otherwise cause closing of fluid flow channels between such plates and for controlling distribution of uid flow along the heat exchange fluid flow paths of said assembly formed by said channels.

A further object of the present invention is to provide a heat exchange plate for horizontal disposition in a heat exchange assembly of horizontally stacked heat exchange plates including means for trapping a gasket positioned between said plate and an adjacent plate in a heat exchanger assembly to prevent extrusion of the gasket during operation of the heat exchange assembly.

A further object of the present invention is to provide a heat exchange plate for horizontal disposition in a heat exchange assembly including means for trapping a flow port portion of a gasket disposed between said plate and -an` adjacent plate to prevent extrusion of the port defining portion of the gasket during operation of the heat exchange assembly.

A still further object of the present invention' is to provide a heat exchange assembly employing horizontally disposed heat exchange plates to provide three fluid How heat exchange paths in the assembly.

Another object of the present invention is to provide a heat exchange assembly employing horizontally disposed heat exchange plates to provide three uid flow heat exchange paths, said paths fbeing in counter-current flow relation.

Yet another object of the present invention is to provide a method of horizontally stacking or nesting heat exchange plates to provide three fluid flow paths in heat exchange relation.

Still another object of the present invention is to provide a method of stacking or nesting heat exchange plates horizontally to provide three uid ow paths in heat exchange relationship, said paths ybeing in countercurrent ow relationship.

A further object of the present invention is to provide a method of supporting horizontally stacked or nested heat exchange plates.

These and other objects, features and advantages of the present invention will become readily lapparent from a careful consideration of the following detailed description when considered in conjunction with the laccompanying drawings, illustrating preferred embodiments of the present invention, wherein like reference numerals and characters refer to like and corresponding parts throughout the several views, and wherein:

FIG. 1 is a. generally schematic view of a desalination system employing a heat exchange assembly constructed in accordance with the principles of the present invention.

FIG. 2 is an enlarged top view in elevation, and broken to facilitate illustration, of the heat exchange assembly of FIG. 1.

FIG. 3 is a side view in elevation of the heat exchange assembly of FIG. 1.

FIG. 4 is an enlarged end view in elevation taken along line 4 4 of FIG. 2.

FIG. 5 is a view in section taken along line 5 5 of FIG. 2.

FIG. 6 is an enlarged fragmentary View in cross section taken along line 6 6 of FIG. 5.

FIG. 7 is a fragmentary view in elevation taken along line 7-7 of FIG. 6.

FIG. 8 is a broken view taken along line 8-8 of FIG. 2.

FIG. 9 is a View taken on line 9-9 of FIG. 8, illustrating porting and gasket features of the heat exchange plates of the present invention illustrated in FIG. 1.

FIG. 10 is a view in perspective of plate support and flow distribution means employed in the heat exchange assembly of FIG. l.

FIG. 11 is a generally diagrammatic view illustrating a plate arrangement for defining fluid flow paths through the assembly of FIG. l.

FIG. 12 is a side -view in elevation of another embodiment of a three fluid ow path heat exchange assembly, broken to facilitate illustration.

FIG. 13 is a top view of the heat exchange assembly of FIG. 12 broken to facilitate illustration.

FIG. -14 is a generally schematic view illustrating the three fluid flow paths of the assembly of FIG. 12.

FIG. 15 is a side view in elevation of a heat exchange assembly similar to the assembly of FIG. l2 having only two uid flow paths in heat exchange relation.

FIG. 16 is a top view in elevation of the assembly of FIG. l5 broken to facilitate illustration.

FIG. 17 is,an enlarged fragmentary view in partial elevation of the port arrangement of a heat exchange gasket and plate assemblyfor employing two fluids in heat exchange relation.

FIG. 17a is a view in section taken along line 17a-17a of FIG. 17.

FIG. 18 is a generally diagrammatic view of the fluid How path system of the heat exchange assembly of FIG. 15.

FIG. 19 is a view taken along the line 19-19 of FIG. 17.

FIG. 2O is an enlarged fragmentary view of a modification of the corner trapping ange arrangement 0f FIG. 17.

Although the present invention has a variety of applications, a suitable environment therefor appears in FIG. 1 and comprises, in general, a desalination system for producing potable water, sweet water, from sea Water.

Sea water, which has been pre-filtered, is brought into the system through a sea water inlet pipe 10 and passed through a de-aerator 12 where dissolved gas is removed from the sea water. The sea water is the delivered by a pump 14 to a heat exchange assembly 16, constructed in accordance with the present invention, where the incoming sea water is placed in a three uid heat-exchange relationship with (l) t-he potable water final 'product and (2) with concentrated brine both of which are being withdrawn from the system, to provide there-v by a three fluid flow heat exchange system.

The sea water entering the system will normally be at ambient temperature, such as, for example, 76 F. and will normally contain about 3.5% by weight of salt, the salinity of thesalt water depending, of course, upon the geographical location from which the sea water is to be extracted.

As hereinafter described, the sea water leaving the heat exchanger 16 will be at a temperature of approximately 30 F. and is delivered through pipe 18 into an evaporating chamber 20 illustrated by the dotted lines. The sea water enters the evaporating chamber 20 near the top thereof, and the sea water, upon entering the evaporating chamber 20, thereafter ows downwardly, preferably over distributor means (not shown) so that the :incoming sea water has a large surface exposure for evaporation in the evaporating chamber 20.

The interior of the evaporating chamber 20 is maintained at a low pressure, approximately 3.2 mm. Hg (millimeters.of mercury) by a vacuum pump (not shown). Due to the fact that `the interior of the evaporating chamber 20 is at such low pressure, sea water,

will flash-evaporate therein. At the freezing temperature of sea Water, the heat of vaporization is approximtaely 1074 B.t.u. per pound and the heat of fusion Vof ice is about 144 B.t.u. per pound. As vapor is produced by vaporization, heat is removed from the remaining liquid, and. ice is formed from the tliquid. Due to the differences in heat of vaporization and heat of fusion, approximately 71/2 pounds of ice will be produced for each pound of water vapor. The ice so produced is substantially pure water ice with no appreciable lamount of salt contained therein. When continuous operation of the system is established, the temperature within the evaporating chamber will be approximately 24.8 F. The vapor formed will be pure water vapor. Thus, upon removal of the pure water from the incoming sea Water by the vaporizing and freezing, the

remaining sea water becomes a more concentrated salt solution.

While theoretically an excess of 75% pure water by weight could be removed in t-he form of vapor and ice, it has been found that removing approximately 50% by weight of pure water is in the range of greatest efficiency; thus, if approximately 50% of the water is removed as vapor and ice, the remaining brine solution will consist of approximately 7% by weight of salt.

It will be .appreciated that the vaporization of water, with the consequent formation of vapor and ice, is :a function of time since heat must be trans-ferred, and. since also the rate of evaporation is proportional to surface area. In order that the sea water remain in the evaporating chamber 20 for a suicient period of time to form vapor and ice and to offer large surface exposure of the sea water, distributor means (not shown) should be disposed within the evaporating chamber 20. A suitable distributing means is described in detail in the copending United States application for patent of .lohn Hans Davids, Serial No. 85,522, filed lan. 30, 1961, for Means For Freezing Exposure of Salt Water in a Salt Water Purification System, the disclosure of which is hereby incorporated herein fby reference.

The mixture of brine with the ice crystals therein is withdrawn from the bottom of the evaporating chamber Z0 through a pump 24, and this mixture of brine and ice crystals has a temperature of approximately 24.8 F.

This mixture of brine and ice crystals is then delivered to a separator-washer or counter-washer 26, in which the ice is separated from the concentrated brine and the ice is washed free of occluded salt and salt adhering to the surface of the ice crystals. The ice-brine mixture enters the lower end of the separator-washer under pressure and the column of the separator-washer 26 becomes essentially full of ice crystals.

The pressure exerted by the entrance of the mixture at the bottom of the counter-washer 26 forces the cylinder of ice packed therein upwardly, and the lbrine forces its way through the ice pack, out through -a screen 28. A' pump 30 removes the brine from a jacket 32 around the lower end of the counter-washer. The pressure drop, created by forcing brine through the ice pack Within the column, exerts a great force on the column of packed ice and which moves the column of packed ice upwardly. Thus, the column of packed ice within the counter-washer continuously Imoves upwardly. At the upper end of the counter-washer is a motor driven scraper or Wiper 34 which wipes off the top of the upwardly moving column of ice and delivers the ice into a trough 36. Spray heads 38 are provided at the top of the counter-Washer 26 for spraying sweet water supplied by pipe 40 on to the top of the porous column of ice, which water runs downwardly over the advancing column of ice to wash any adhering or occluded lbrine on the surface or in the interstices of the ice.

Sweet water is added by means of pipe 42 to the ice in the trough 36 so as to produce a solution of sweet water and ice suspended therein which can bepumped.

The ice is introduced into a vacuum chamber by supplying sweet water to the ice to provide a liquid with the ice suspended therein, the resulting mixture may, therefore, be more readily handled, and the liquid. prevents the breaking of the vacuum within the vacuum chamber. A pump 44 is shown for delivering the mixture of ice and sweet water through a pipe .46 to a condensing chamvber S0.

rlhe condensing chamber 50 is an annular chamber, having its inner dimension defined by the wall of the concentric evaporating chamber 20 and its -outer dimension dened by an outer wall 52 which preferably is insulated as indicated at 54 in FIG. 1 to prevent heat from entering the system.

A plurality of trays (not shown) arranged concentrically within the conducting chamber 50 may be provided for receiving the mixture of ice and sweet water, such as the condensing chamber tray arrangement disclosed in United States application for patent to evaporating and condensing chamber apparatus, Serial No. 103,112, and tiled Apr. 14, 1961.

A radial compressor 55 is positioned Within the upper end of the condensing chamber 50 and is provided with an axial intake opening 56 in communication with the evaporating chamber 20 and Wit-h Aa circular outlet 58 communicating with the condensing chamber 50.

Vapor formed in the evaporating chamber 20 is drawn into the central intake opening 56 of the compressor 54 and delivered radially outward into the condensing charnber 50 through the outlet 58. The vapor is thus compressed and the compressor 54 maintains the condensing chamber 50 at a pressure of approximately 4.6 mm. Hg. The vapor delivered by the compressor into the condensing chamber passes downwardly into contact with the ice disposed in the condensing chamber and simultaneously causes the vapor to condense and the ice to melt. The Sweet water thus produced is withdrawn from the lower end of the condensing chamber 50 through a pipe 60, which delivers a portion of the sweet water back to the counter-washer 26 through pipes 40 and 42 for ice washing and for mixing with the ice. The major quantity of the sweet water product passes through the pipe 62 to the heat exchanger 16.

One of the greatest diculties encountered in prior art vacuum freezing systems is their inability to efficiently and economically handle and transport the large volumes of vapor that exists for any system produced in a meaningful amount of sweet water, particularly when it is recognized that we are dealing with such low pressures that approximately 4500 cubic feet of vapor at these pressures is required to provide one pound of water vapor. Without the arrangement, systems and methods above described, expensive and extremely large compressor shrouds and conduits would be'required for transporting the vapor. Normally, to move any such large volume, a multi-stage axial compressor would be required, and this, alone, without considering the conduit and its size and expense, would make the system uneconomical.

Ideally, the vapor should be delivered to the condensing chamber at saturation conditions of pressure and temperatures so that the vapor will condense on the 32 F. ice, and the ice will take out of the vapor 1074 B.t.u. per pound of vapor condensed and thereby cause the 32 F. ice to melt by each pound absorbing each pound of ice absorbing 144 B.t.u. However, due to losses because of heat entering the system and superheating of the vapor by the compressor, the excess vapor to provide thermal balance in the system is not condensed in the condensing chamber and thus some means must be provided for removing this excess vapor from the system. The provision of secondary refrigeration coils in the evaporating chamber to cause formation of additional ice therein will not adequately solve this problem because of the formation of additional vapor as a result of the increased ice production due to employment of the secondary refrigeration coils and an additional disadvantage inherent in the employment of such secondary refrigeration coils in the evaporating chamber is that additional surfaces are provided in the evaporating chamber 20 on which ice may collect and form. The ice so formed may collect to an extent suflcient to cause interruption of the contiguous process of the system. Moreover, employment of such refrigeration coils in the evaporating chamber will not solve completely the excess vapor problem caused by superheating of the vapor in the compressor 54. In the copending application, Serial No. 703,112, tiled Apr. 14, 1961, secondary refrigeration coils are shown disposed in the condensing chamber 50 for condensing excess vapor in the condensing chamber. However, with this arrangement, the possibility always exists that the ice, in building up on the coils, Will reach'a cross-sectional thickness sutiicient to block ow of the pure water from the condensingy chamber, particularly in view of the position of the coils in the bottom of the condensing chamber. The compressor itself will not provide an area for possible reduction in the quantity of excess vapor because the compressor superheats the vapor. Thus, at all critical stages in the system wherein the excess vapor problem might be solved other 4design parameters outweigh modification or adaptation of the design of the condensing chamber, the compressor or the evaporating chamber to solve this problem. It will be appreciated that design changes or modifications downstream of the condensing chamber will not s olve the excess vapor problem inthe condensing chamber.

An adequate solution to the excess vapor and heat removal problems aforementioned is provided by the copending United States application, Serial No. 195,083, tiled May 16, 1962.

Heat exchange system In general, in the operation of the heat exchange assembly 16 appearing in FIG. 1, the sea water, to be converted into potable water, is introduced under pressure through the conduit 10 connected to an inlet 4 of an inlet manifold 5 into the heat exchange assembly 16, and, after flowing through a labyrinth reversing flow path through a first plurality of ow channels defined by aA plurality of horizontally stacked or nested heat exchange plates 17, is discharged from the heat exchange assembly 16 through a manifold 19 having an outlet 21 connected to the line 18 for supply thereof to the evaporating chamber 20.

Brine, employed as a coolant, is supplied from the chamber 32 through a conduit 33 into the heat exchange assembly 16 by connection thereof with the inlet 23 of an inlet manifold 25 of the heat exchange assembly. In the heat exchanger 16 the brine follows a labyrinth flow path in counter-current heat exchange relation to the flow path of the sea water through a second plurality of ow channels defined by the stacked heat exchange plates 17. The brine is then discharged from the heat exchange assembly 16 through a conduit 27 connected to an outlet 29 of an outlet manifold 31 of the heat exchange assembly 16.

Similarly, fresh water may be employed as a coolant for the sea water. The fresh water is supplied to the heat exchanger 16 from the conduit 62 which is connected to an inlet 33a of an inlet manifold 35 of the heat exchange assembly 16. The fresh water follows a labyrinth flow path through a third plurality of channels defined by the stacked heat exchange plates in counter-current flow and in heat exchange relation to the ow path of the sea water through the heat exchanger and is discharged from the heat exchange assembly from the outlet 6 of a manifold 7 of the heat exchanger through a conduit 37 which may empty into a reservoir 39 from which the potable fresh water may be withdrawn for subsequent use or disposition.

Thus, the heat exchange assembly 16 shown in FIG. 1 is adapted to perform a heat exchange function employing one or more different or similar coolant fluids, each of which may be maintained in counter-current flow and in heat exchange relation with the sea water continuously or intermittently throughout the entire ow thereof through the heat exchange assembly 16 during operation of the desalination system.

The construction and operation of the heat exchange assembly 16 of FIG. 1 will now be described.

Heat exchange assembly-in general Referring to FIGS. 2-5, the heat exchange assembly 16 comprises, in general, a heat exchange plate support assembly and a plurality of horizontally disposed heat exchange plates 17, preferably constructed of aluminum and preferably having a cross-sectional dimension of from about twenty hundredths to about thirty-two hundredths of an inch. It will be appreciated, therefore, that the heat exchange plates are quite thin. Heat exchange plates 17 of such thinness having a length dimension of approximately 14 feet and a width dimension of approximately 2*/2 feet have been successfuly employed in a heat exchange assembly corresponding to that appearing in FIG. 1.

These heat exchange plates 17 are grouped in stacked series and are supported for operation in a new and improved heat exchange plate support assembly constructed in accordance with the present invention.

Plate support assembly As shown in FIGS. 3 and 4, the heat exchange plate support assembly includes a generally planar or flat surfaced and horizontally extending bottom support plate 49 supported on a plurality of stanchions 50, a generally planar or flat surfaced and horizontally extending top support plate 51 and an intermediate planar or flat surfaced and horizontally extending support and reinforcing plate 53; These support plates 49, 51 and 53 are ported in a manner hereinafter more fully described to permit flow of three fluids in heat exchange relation through the heat exchange assembly 16.

The plate support assembly of the present invention includes in addition to support plates 49, 51 and 53, a plurality of horizontally disposed separator or spacer support plates 57 located between the bottom support plate 49 and the intermediate support plate S3, and a similar plurality of horizontally disposed separator or spacer support plates 55 located between the intermediate support plate 53 and the top support plate 51.

The spacer plates 55 and 57 are located between predetermined sets of preselected numbers of heat exchange plates 17 and are each ported to provide a plurality of zones communicating the channels of the separate flow paths'of the three fluids which are in heat exchange relation. Each of the spacer plates 55 and 57 provides means for reinforcing and strengthening the sets of heat exchange plates 17 therebetween and the plurality of Aspacer plates 55 and 57, when so disposed, cooperate with the support plates 49, 51 and 53 to strengthen and reinforce the heat exchange assembly 16.

The plate support assembly for the heat exchange plates 17, in addition, includes a plurality of vertically extending and peripherally spaced rods 59, as clearly appears in FIGS. 1 and 3, which pass through apertures formed in both the bottom and top plates 49 and 51 which are threaded through the intermediate plate 53. These rods 59 provide means for selectively varying compression of the heat exchange plates 17 disposed between the bottom, intermediate and top plates and for facilitating assembly of the plates.

It will be observed that the bottom support plate 49, intermediate support plate 53, and top support plate 51 are of an area dimension greater than the corresponding dimension of both the heat exchange plates 17 and the spacer plates 55 and 57. The plate 53 is bored, and the -bore thereof is threaded to receive in threaded engagement therewith the externally threaded rods 59. Thus, the rods 59 serve as means which cooperate with nuts 61 and 61 (FIG. 3) to apply the compression pressure required to assemble the heat exchange assembly 16 by contact only with the three support plates, i.e., the bottom plate 49, the intermediate plate 53, and the top plate 51, and this compression pressure, therefore, is not exerted directly on the thin heat exchange plates or spacer plates but exerted on the heat exchange plates by the compression of gaskets between the heat exchange plates. It will be appreciated that, with heat exchange plates of such thin cross-sectional dimension as aforementioned, the pressure applied by4 threading of the rods 59 to provide a leakproof heat exchange assembly, if applied directly to the heat exchange plates by threading of the rods therethrough, would cause the marginal ends of the heat exchange plates to buckle, and thereby permit outward extrusion of gaskets which are disposed between the heat exchange plates, and consequently would result in an inoperative assembly 16.

To further strengthen the heat exchange plate support assembly and to permit alignment of the heat exchange plates 17, the means for strengthening and aligning the plate support assembly of FIG. 1 includes a plurality of sets of peripherally spaced and vertically extending bars carried by the support plates in contact with the leading edges of both the spacer plates 55 and 57 and the heat exchange plates 17 as clearly appears in FIG. 3. The aligning and strengthening means includes a plurality of peripherally spaced ybars 63 which extend substantially perpendicular in .a vertical direction from the longitudinal axis of the intermediate plate 53.

Each of the bars 63 is T-shaped with the wider inner surface thereof being flat (FIG. 6) and in contact with both a plurality of spacer plates 55 and 57 and a plurality of heat exchange plates 17 for proper alignment and maintenance of such alignment thereof in the heat exchange assembly and to prevent slipping or translation thereof during operation of the heat exchange assembly. Each bar 63 has a mounting flange 65 to secure the bar, as by bolts 67, to the intermediate support plate 53. It will be observed that two bars 63, in axial alignment, are employed to so align spacer plates 55 and 57 and heat exchange plates 17 both above and below the intermediate support plate 53.

A plurality of peripherally arranged bars 68 are mounted on the top support plate 51 in alignment with a similar plurality of bars 69 -mounted on the bottom support plate 49 which cooperate with the bars 63 mounted on the intermediate plate 53 to properly align and strengthen the spacer plates 55 and 57, and the heat exchange plates 17, and thus the heat exchange assembly 16. It will also -be observed that the bars 63, 68 and 69 are alternately arranged around the periphery of the heat exchange assembly.

In assembling a heat exchange assembly comprising a plurality of horizontally nested or stacked plates 17 which are of thin cross-sectional dimension, one of the problems encountered is the proper distribution of the assembling pressure exerted on the assembly and that pressure exerted particularly on the top support plate 51 and bottom support plate 49 during threading of the rods 59. It will be appreciated that, because a plurality of rods 59 will be selectively threaded through the intermediate plate 53 to apply the correct compressive force in assembling the heat exchange plates 17 into a leakproof assembly, the possibility exists that, in the threading process, the top or bottom support plates may become misaligned as a result of the unequal distribution of pressure applied thereto in threading of nuts 61 and 61', and thus, his initial misalignment will be subsequently reflected in the alignment of the later stacked heat exchange plates and spacer plates, thereby necessitating continuous assembly and disassembly of the plates, until the proper alignment is achieved.

To assure that a substantially uniform distribution of the force will be applied to the top plate 51 during threading of the rods 59 and thereby to minimize the possibility of attendant misalignment of the heat exchange plates, the top support plate 51 carries a centrally disposed and axially extending force-transmitting inverted channel member 73 (FIGS. 2 5) of suitable material which has welded thereto (FIG. a plurality of transversely extending and spaced rigid straps or brackets 77. Each of vthe straps 77, as clearly appears in FIG. 5, comprises in cross section a horizontally extending central body 79 overlying and connected to the base 81 of the inverted channel member 73, a pair of arms 83 which radiate downwardly at an angle from each side of the central body 79 towards the upper surface of the top plate 51. Each of the arms 83 has an outwardly extending horizontal flange 85 which has therein a bore in axial alignment with the bore of the top plate 51 for permitting passage therethrough of one end of one of the rods 59. The nuts 61 and 61' are in threaded engagement and employed to pull the plates together. The rods 59 are slideable through the bores of both plates 51 and 49 and are in threaded engagement with intermediate plates 53. It will, therefore, be appreciated that any force to be transmitted to the top plate 51 applied to the flange 85 in the operation of the rods 59 to initiate compression of the. heat exchange plates 17 during assembly thereof will be transmitted through the arms 83 and body 79 to the channel member 73 and from the channel member will be distributed thereby more evenly to the top plate 51 as compared to the force transmission which would otherwise occur if the channel member 73 and straps 77 were not employed.

Similarly, to assure that a substantially uniform distribution of the weight of the assembly and that the assemblying force be applied to the bottom plate 49 during threading of the nuts 61 4to thereby minimize the possibility of attendant misalignment of the heat exchange plates, the bottom support plate 19 carries a centrally disposed and axially extending force-transmitting channel member 37 (FIGS. 2-5) of suitable material, such as steel, which has secured thereto (FIG. 5) a plurality of transversely extending and spaced rigid straps or brackets 89.

Each of the straps 89, as clearly appears in FIG. 5, comprises in cross section a horizontally extending central body 91 overlying and connected as by welding, to the base 93 of the channel member 87 and a pair of arms 95 which radiate upwardly at an angle from each side of the central body 91 towards the lower surface of the bottom plate 49.

Each of the arms 95 has an outwardly extending and horizontally disposed flange 97 which has therein a bore in axial alignment with the bore of the bottom support plate 49 for permitting passage therethrough of one end of one of the rods 59.

It will, therefore, be appreciated that any force to be transmitted to the bottom support plate 49 in the operation of the rods 59 to initiate compression of the heat exchange plates 17 during assembly thereof will be applied to the anges 97, 97. The pressure, therefore, applied to the flanges 97, 97 will be transmitted to the arms 95, 95 and the body 91 of the strap 89 and to the channel member 87 and will be distributed thereby more evenly to the bottom support plate 49, as compared to the force transmission which would otherwise occur if the channel 87 and the strap 89 were not employed.

With the lheat exchange plate support assembly above described, lateral translation and transverse slippage of the heat exchange plates 17, relative to one another when assembled, is substantially minimized, and, by the simple expedient of adjusting the pressure applied on the stacked plates by turning of the nuts 61, 61 a predetermined alignment of the plates may be effected, during assembly thereof, which prevents slippage of the plates and which may be maintained during normal operation of the heat exchange assembly 16. In addition, with the now described heat exchange plate support assembly, an eicient and economical horizontally extending heat exchange assembly comprising a series of sets of a plurality of stacked and horizontally extending heat exchange plates 17 may be constructed in such a manner as to provide at least six individual sets of such plates 17 separated by support spacer plates 55 and 57 and the intermediate plate 53, as exempliiied in FIG. 5.

The details of the construction of the heat exchange plates 17 and the cooperative relationship between the plates 17 in each set of plates between the spacer plates 55 and 57 will-now be described.

Heat exchange plate c0nstructi0ngelteral As appears in FIG. 6, each of the heat exchange plates 17 is of generally rectangular shape, and is provided with a plurality of spaced and recessed downwardly extending protuberances. or dimples 101 throughout the effective heat exchange flow path area of each plate 17. Preferably dimples 101 are `formed within an inner rectangular area of each plate 17 which comprises approximately 83% of the total flow area of each plate. The dimples 101 are provided to provide turbulence and increase the area of heat transfer contact of the fluid flowing in the channel defined by a pair of adjacent heat exchange plates 17. The recesses provided by the dimples 101 in each heat exchange plate 17 cooperate with the dimples 101 of the adjacent flow channel defining heat exchange plate 17 to enhance the degree of turbulence of the fluid flowing through the channel 105 and to thereby increase the heat exchange effect of the lheat exchange assembly. It will be observed that the dimples 101 in each heat exchange plate 17 provides turbulence inducing means in each of the two flow chaddels 105 defined by that plate and two adjacent plates 17 and, in addition, increases the effective heat exchange area of the plates. Each heat exchange plate 17 is provided at each side with three flow ports. To the right as viewed in FIG. 9 three ports 138, 140 and 142 are shown, it being understood that three similar ports. (not shown) are provided in the opposite side of each plate.

Gasket construction Each heat exchange plate 17 in each set of heat exchange plates between each of the spacer plates and between the intermediate and adjacent spacer plates is separated from the two adjacent plates by a gasket 103 which is of generally rectangular shape and which is constructed of elastomeric material, such as rubber, or other material which is inert to the fluid coming in contact therewith in passing through the flow channel 105 dened by each adjacent stacked heat exchange plate.

Each of the gaskets 103 is preferably of a cross-sectional thickness sufficient to maintain the adjacent heat exchange plates spaced from one another, when assembled, and to thereby permit flow of fluid from and into the channels 105 defined by each pair of adjacent heat exchange plates 17.

The details of construction of the gaskets 103 and their cooperative relationship with the plates 17 are illustrated in FIGS. 6-9. Referring to FIG. 9, each of the rectangularly shaped gaskets 103 includes two parallel elongated legs 107 and 109 `formed integrally with a pair of opposed and parallel extending side legs 111 and 113 (FIG. 8) in which ports are formed to provide communication between corresponding flow channels inthe heat exchange assembly 16. It will be observed from a study of FIGS. 8 and 9 thatthe length and width dimensions of the gaskets 103 are less than the corresponding dimensions of the heat exchange plates 17 and define an opening corresponding in dimensions to the effective dimpled heat exchange area of the plate on which the gasket is seated. That area of `the plate 17 on which the gasket seats is flat and the gasket serves to prevent leakage from the effective dimpled flow area of the plate 17. The opening of the gasket defines the flow channel 105 with the adjacent plates 17.

To minimize the possibility of outward extrusion. of the gasket 103 between the adjacent heat exchange plates 17 as a consequence of the pressure applied thereto by the weight of the plate above the gasket, the Weight of the successive plates above each plate, and primarily the y pressure of the fluid flowing through the flow path channels 105 defined by adjacent plates, each of the gasket contacting and channel defining heat exchange plate 17 is provided with (as appears in FIGS. 6, 7 and 9) a plurality of separate downwardly turned flanges 116 which are spaced around the periphery of each plate 17 and trap the gaskets. The turned flanges 116 are spaced inwardly of the edge 118 of `the plate 17 so that the plates may be contacted by the bars 63, 68 and 69 for aligning thereof. FIG. 6 illustrates this feature with the bars 63.

The trapping flanges 116, therefore, cooperate with the other parts of the plate support assembly to provide a means for aligning the plates 117 and for preventing leakage of fluid from the flow channels defined by adjacent plates.

It will be observed that the channel defining plate 17 of each set'of plates above and below the intermediate plate 53 is preferably separated from the intermediate plates by flat surfaced gaskets 103a and 103b, respectively, to space the heat exchange plates from the intermediate plates 53. Similar gaskets space the top and bottom plates from the heat exchange plates.

Another reason that the length and width dimensions of the gasket 103 are less than the corresponding dimensions of the heat exchange plates 17 is to permit the plate flanges 116 to confine the gaskets and thereby provide a leakproof assembly during assembly of the heat exchange assembly. From FIG. 6 it will also be observed that each of the flanges 116 is of a height less than the corresponding height of the adjacent side legs 111 and 113 of the gasket 103 to permit variable adjustment of the pressure applied to the heat exchange assembly by threading of the rods 59 during assembly of the heat exchange assembly, for example, in the event it becomes necessary to make such adjustment for the purpose of preventing leakage from the heat exchange assembly.

Each side leg 111 and 113 of each gasket 103 is provided with three aligned ports, 114, 117 and 119, the side 111 and gasket ports 114, 117 and 119 being illustrated in FIG. 9. The three gasket ports 114, 117 and 119 overlie the complementary ports 138, and 142 formed in the plate 17. The ports 114 and 138 serve as an outlet port for one of the coolants employed in the system, either brine or fresh water, and, as appears in FIG. 9, ports 140 and 142 serve as by-pass ports for the other coolant and for sea water. 'Ille opposite side of each plate 17 (not shown) is ported to provide an inlet port for one of the coolant fluids, brine or sea water, and two by-pass ports. Preferably the inlet ports of the channels of the two coolants are each located in a position diagonally opposite the corresponding outlet port 138 throughout the assembly to provide a greater heat transfer area in the channel 105 as indicated in FIG. 9 by the arrows. 'I'he gaskets preferably are of medium hardness, having, for example, a 50 durometer reading.

The preferred flow pattern of the sea water, however, in its channels 105 throughout the assembly is from the intermediate inlet port (not shown) of the three ports formed in the gasket and plate 17 at one side of the flow channel 105 to the corresponding intermediate outlet port between the other two ports formed in the gasket and plate at the opposite side of each flow channel 105. it will be appreciated, of course, that, depending upon the arrangement and number of heat exchange plates and gaskets employed to define a flow path through the heat exchange assembly 16, the direction of flow of one of the fluids in a three fluid system in which one fluid flows in counter-current relation to the other fluids may be either from the right to the left or from the left to the right as viewed in FIGS. 9 and 1l.

Each by-pass port 140 and 142 is provided to permit flow past a channel 105 employed for a different fluid, either coolant or sea water, as more fully discussed hereinafter.

It will be `observed that each gasket side 111 in which the ports 114, 117 and 119 are formed is provided with an inner integral strip 144 adjacent to and defining the inner side of the by-pass port 117 to permit flow of one fluid, such as sea water, through the by-pass port 140 adjacent a flow channel 105 and into that channel 105 of another preselected fluid, such as fresh water, and also provided with an inner strip 146 adjacent to and defining the inner side of port 119, for preventing flow of the other coolant, brine, from the by-pass port 142 into the fresh water channel 105 illustrated in FIG. 9. However,

13 a strip is not provided adjacent port 138 so that the channel 105 communicates, through a gap outlet space 143, with the port 138 to permit flow of the preselected fiuid, fresh water, from the channel 105. Similar strips and gaps are provided for the inlet port and by-pass ports in the opposite side 113 of each gasket.

The Weight of the top plate 51, the heat exchange plates and the gaskets 103 and the compressive force of the assembly has a tendency to close each of the channels 105, particularly adjacent the inlet port (not shown) and outlet port gaps 143 of each of the channels 105 because an inner strip 140 or 142 is not provided by the gasket to support the weight of the plates at the gap above the lower plate dening the channel 105 (FIG. 9).

In accordance with the present invention, a corrugated strip 150 of suitable material, such as aluminum, is disposed onl each of the channel defining heat exchange plates 17 adjacent both the inletports (not shown) and the outlet ports 138 in gaps 143 to separate the plates defining the channels 105 and thereby to prevent the compressive force due to assembly of the plates from closing the gaps 143 communicating both the inlet port (not shown) of each of the ow channels 105 and the correponding outlet ports 138. These plates 150 not only prevent closing of the communicating gap 143 between each inlet port and the corresponding outlet port 138 and fiow channel 105, but also apply compressive force on the adjacent channel defining gasket so as to prevent leakage therefrom which would otherwise occur as a result of extrusion of the gaskets caused by water pressure. The strip plate 150 is corrugated as appears in FIGS. 9 and 10, and, in addition to supporting the plates to prevent closing of the gap between the channel defining plates, the strips, because of their corrugated design, provide a smooth flow pattern to the uid iiowing into and from the flow channel 105. It will appreciated that the cross flow or diagonal flow pattern of the channels for the brine and sea water, as appears in FIG. 9, tends to concentrate the ow pressure of the flowing coolant in the vicinity of both the inlet port and the outlet port 138 of the channel 105. This pressure tends to create flow surges into and from the channel 105 .and through the manifolds communicating therewith which tend to reduce the eiciency of the heat exchange assembly7 as the direction of iiow of these uids is alternately reversed from preselected flow channel to preselected fiow channel along the flow channel along the ow paths of the fluids. With employment of the plates 150 such fiow surges are minimized, the gaps 143 provided for communicating the fiow Channels 105 with the inlet ports and outlet ports 138 are maintained open, and the efficiency of the heat exchange assembly is maintained at a practical level.

A problem associated with this type of gasket and heat exchange plate design for a heat exchange system is that the pressure exerted on the gasket by the fiuid flowing in the flow channel has a tendency to force the gasket strips 146 and 144 defining one side of the by-pass ports 117 and 119 inwardly into the by-pass ports 140 and 142, respectively, which would cause undesirable leakage and mixing of fiuids in the by-pass ports 140 and 142 and flow of one or either of the fluids owing through these by-pass ports into the flow channel 105 of the third iiuid. to prevent such extrusion of `the gasket strips 144 and 146, the inner portion of each heat exchange plate 17 defining the ports 140 and 142 is provided with a plurality of spaced and downturned gasket strip trapping anges 152. For purposes of illustration in FIG. 9, three of such spaced flanges 152 are shown. These flanges 152 are of a length less than the radius of the dimples 101 (FIG. 4) in the heat exchange plates or equal thereto to permit compression of the gasket by threading of the nuts 61 and 61. Thus means are provided for the prevention of extrusion of the inner port defining strips 144 and 146 of each of the by-pass ports formed in the gaskets 103.

Three fluid flow pattern A three fluid flow pattern representative of the reversing flow paths defined by the heat exchange assembly 16 shown in the drawings appears in FIGS. 11 and 8. In FIG. 8 the freshwater flow path is shown to illustrate the ow pattern of a representative uid in the three Vfiuid ow heat exchange assembly and .is reperesented by the iiow path of the fresh water through the inlet 33a and mani- `fold 35.

Referring to FIG. 8, the fresh water flow path is such that Ithe fresh water enters under pressure through the inlet 33a and is supplied to the manifold 35 which communicates with a port 160 formed in the top plate 51. The port communicates with the vertical flow path zone 162 defined iby the ports of .the plurality of stacked alternated gaskets and heat exchange plates 17 in the set 'of heat exchange plates provided .betwen the top plate .port 168 in the spacer plate 55, and to the inlet ports 169 and 169 of two other pre-selected fiow channels 105 between the spacer plate 55 and the lower spacer plate 55 shown in FIG. 8. It will fbe observed that one of the heat exchange plates centrally located between the top plate 51 and the spacer plate 55 lhas a closed end 171 to prevent upwardly flow of the fluid in the vertical lzone 166 `de'lined by the ports of the gaskets and heat exchange plates. Similarly, a heat exchange plate 173 located intermediate the spacer plate 55 and the spacer plate 55 is closed at one end lto prevent fiow of the uid from the zone 166 upwardly. The heat exchange plates 1711 and 173 thereby provide means for preventing mixture of the lfiuids as they flow through their respective zones from pre-selected channel 1105 to pre-selected channel 105.

The fresh water flow pattern is such that the fresh water flows in the channels 105 above the -spacer plate 55 in a direction from right :to left, and below the spacer plate 55 flow thereof is reversed and fresh water flows in a direction left to right as viewed in FIG. 8. The plate 173 also provides means for reversing thet direction of fiow of the fresh water `between the spacer plates 55 and y55 to increase the number of passes the fressh water makes in counter-current flow relation .with the sea water whereby the total length of the iiow path of the fresh water through the heat exchange assembly 16 may be increased and thus provide an increase in the heat exchange effect of the system. The fresh water iiows through lthe preselected heat exchange iiow channels 105 located between the spacer plate 55 and the heat exchange plate l173 to the outlet ports 175 and 1-77 land into the vertical zone 179 (KFIG. 8) defined by the por-ts of stacked gaskets and plates. As viewed in FIG.. lil the right hand ends of the spacer plates -55 and 55 are not ported iso as to prevent mixture of fluids in the vertical liow zones 162 and 179 ('FIG. 8). From the zone 1179, the direction of flow of the fresh Iwater is again reve-rsed and the fresh `water fiows through inlet ports 181 and 183 into preselected flow channels 1105, The fresh water fioiws through the channels 105 and out the outlet ports 185 and 187 thereof into the vertical zone 189 defined bythe ports of the stacked gaskets and plates and then through a port 200 formed in the spacer plate 55. From the Zone 189 the fresh .water then flows into .the inlet ports 191 and 193 of preselected fiow channels 105 between the spacer plate 55' `and intermediate plate 53.

:From these channels 105 the fresh water flows through the outlets 195 and l197 thereof into an outlet zone `199 defined by the ports of stacked gaskets and plates and through a port 201 formed in the intermediate plate 53.

The di-rection of flow of the fresh water is reversed below the intermediate plate 53, as indicated by the arrows in FIG. 8 and is directed through flow channels C105 and flow zones similar to the flow channels 105 and flow zones defined by ports of gaskets and plates of the heat exchange plate arrangement provided above the intermediate plate 53. The spacer plates below the intermediate plate 53 are provided with flow ports 2 02 and 204, respectively, to permit reversal of the direction of flow of the fresh water and the ends 203 and 205 thereof are not ported to permit such reversal and to prevent mixing of fluids above and below the spacer plates. In addition, heat exchange plates 207 and 209, which are, respectively, intermediate the spacer plate 57 and spacer plate 57 and the spacer plate 57 and bottom plate 49, are not ported at their left-hand sides to prevent mixture of the fresh Iwater flowing between pre-selected channels 105 with the other uids and to permit reversal Vof flow off the fresh water in the `arrangement of heat exchange plates VIbelow the intermediate plate 53. As indicated by the solid line a-rrows in FIG. 8, the 4fresh water is discharged from the pre-selected flow channels 105 in the last set of flow channels below the heat exchange plate 209 in-to outlets 211 `and 213 thereof and then into a discharge zone 215. From the discharge zone 215, .the fresh water is discharged through a port'217 formed in the bottom plate 49 and into the manifold 7 for discharge from the heat exchange assembly I16 through the outlet 6.

With the exemplary arrangement of heat exchange plates and intermediate land spacer plates shown in FIG. I11, Ithe direction of flow of the fresh vater Ithrough the heat exchange assembly 16 may be reversed eight times. It will 'be appreciated .that other arrangements of plates may be provided which increases the number of .times reversal of the direction of travel of the fresh water -through lthe heat exchange assembly may be achieved and thus the length of the flow path of the fresh water through the heat exchange assembly may be varied.

As appears in FIG. 1l, the brine flow pattern is such that the brine is introduced as a coolant into the heat exchange assembly 16 through a port 219 formed in the top plate 51 and flows through an inlet zone, as indicated by the dash dot lines, into four pre-selected channels 105 identified by the letter B in the first set of heat exchange flow channels fbetween Athe ltop plate 51 and a heat exchange plate 171.

The sea water flow path pattern is indicated by the dash line arrows in FIG. 11. The sea water to be cooled by the brine and fresh water is introduced through a port 221 located in the bottom plate 4 9 for flow through preselected llow channels 105 located between the bottom plate 49 and the heat exchange plate 209. The preselected channels are identified in FIG. 11 by the letter S. The sea Water flows in counter-current relationship to both the fresh water and brine' in three of the channels 105 between the lower plate 49 and the heat exchange plate 209. The same arrangement of counter-current flow in heat exchange relationship between the sea water and coolants is maintained in the other sets of flow zones defined by the ports of gaskets and plates and in the sets of channels identified in FIG. 11 by the Roman numerals I through VIII.

In the set of channels identified in FIG. l1 by the Roman numeral X and located at the top of the heat exchange assembly between the heat exchange plate 171 and top plate 51, the fresh water is not employed as a heat exchange coolant and in this set of channels X only the brine and sea water are maintained in counter-current heat exchange relationship because the brine, when introduced into the assembly is colder than the sea water and the sea water, in leaving the assembly, is colder than the fresh water. Thus, since the fresh water is introduced into the assembly 16 at the top thereof, the heat exchange effect, if the .fresh water were brought in heat exchange relation with the sea water in this set X would be only to cool the fresh water.

Thus, with the arrangement of plates appearing in FIG. 1l a heat exchange assembly 16 may be provided for three fluids flowing along flow paths in heat exchange relationship and in which the two vcoolants fluids are in counter-current flow relation to the fluid to be cooled thereby. It will be appreciated that by an increase in the number of plates a heat exchange assembly may be provided which provides an increase in the number of flow channels for the three fluids and an attendant increase in the heat exchange effect of the system in accordance with the present invention.

As an example of a three flow system for the heat exchange assembly 16 appearing in FIG. l1, the flow rate of the brine through the heat exchange assembly under ideal conditions should be 44 g.p.m. at an inlet temperature of 25 F. and an outlet temperature of 74 F. The fresh water should have a flow rate through the heat exchange assembly 16 of 44 g.p.m. and an inlet temperature -of 32 F. and an outlet temperature of 74 F. under ideal conditions, and the sea water should have a flow rate through the heat exchange assembly of 88 g.p.m.s at an inlet temperature of 76 F. and an outlet temperature of 30 F. It will be appreciated, of course, that the brine flow rate will be less in flowing through the group X set of heat exchange flow channels of FIG. 1l, because the brine flows through four flow channels 105 in group X and through only two flow channels in the remaining groups as does the fresh water in the remaining groups.

In assemblying the heat exchange assembly 16 it is preferable to first insert the rods 59 through vthe bottom plate 49 and then stack the desired number of heat exchange plates, gaskets, and spacer plates. The intermediate support plate 53 is then placed on the stacked heat exchange plates, gaskets and spacer plates 55 and 55' and the rods 59 threaded through the intermediate plate. The lower nuts 61 are then threaded (FIG. 8) to tighten and compress the heat exchange plates, gaskets, and spacer plates between the bottom plate and the intermediate support plate 53. After the initial compression is applied by the nuts 61', the lower half of the heat exchange assembly may be tested by running water through the flow channels 105 defined thereby to assure that the lower half of the heat exchange assembly is leak proof. By so assembling and testing the lower half of the heat exchange assembly initially the stacking problem is minimized as is the tightening problems necessitated to prevent leakage. In addition such assembly prevents buckling of the stack which might otherwise occur if the upper half of the heat exchange plates were first stacked, and the top support plate 51 assembled, and

tightening of the assembly held in abeyance until suchA had been done.

To assist in aligning and maintaining alignment of the heat exchange plates of the lower half of the heat exchange assembly, the guide bars 69 are connected to the bottom support plate 49, After the lower half of the heat exchange plates, gaskets, and spacer plates are stacked and the intermediate plate is placed thereon, the rods 59 and the guide rods 63 depending downwardly from the intermediate plate are assembled to assist the guide bars 69 in aligning the heat exchange plates below the intermediate support plate 53 before compression of the lower half of the heat exchange plates occurs by threading of the rods 59 to assure a leakproof assembly below the intermediate support plate 53. Afterthe lower half of the assembly is tested and approved, the upwardly depending guide bars 63 are connected to the intermediate support plate 53 to assist in aligning the heat exchange plates, gaskets, and spacer plates which are stacked above the intermediate support plate 53. After a predetermined number of heat exchange plates 17, gaskets, and spacer plates are stacked-above the intermediate support plate, the top plate 51 is then placed on the stack and the guide rods 63 are assisted in maintaining the proper alignment 17 of the plates by the guide `bars 68 depending from the top support plate 51. The upper half of the stacked heat exchange plates above the intermediate plate 53 are then compressed by threading of the nuts 61 on rods 59.

After the plates are compressed a predetermined amount so that the dimples of adjacent plates contact, the entire assembly is then water-tested to assure that not only the upper stack of heat exchange plates is leakproof but also that the entire heat exchange assembly is leakproof. The assembly is now completed and ready for incorporation in the desalination system of FIG. 1.

In the preferred embodiment of the present invention appearing in FIG. 12, the intermediate support plate 53 and the heat exchange plates 171, 173, 207 and 209 of the heat exchange assembly of FIG. 2 are replaced by ported spacer plates 220, 222, 224, 226, 228, 230 and 23.2, which are similar in construction and operation to spacer plates 55, 55', 57 and 57 which remain in the assembly as clearly appears in FIGS. 12 and 14.

In this arrangement of FIG. 12 an additional spacer plate 232 is included in the heat exchange assembly, as well as an additional set of heat exchange plates, identified by the roman numeral XI in FIG. 14, which are located between the bottom support plate 49 and the spacer `plate 232. This spacer plate and additional set of heat exchange plates Xl are employed to provide an additional set of flow channels for the three fluids. With this heat exchange assembly, the directions of ilow of the three fluids through the assembly may be reversed in countercurrent llow relation a total of ten times, thereby providing additional lengths to the total flow paths of the fluids through the heat exchange assembly 16 and thereby providing an increase in the heat exchange effect obtained by the assembly 16.

The spacer plates 220, 222, 224, 226, 228, and 230 and 232 spacer plates 55, 55', 57 and 57 are alternately ported relative to each other to effect the desired reversals of the directions of flow of the three fluids between these plates. The ends 225, 227, 229, 231, and 233 of the spacer plates 22d-230 are closed to prevent mixture of the fluids flowing in the channels 105 between the spacer plates and cooperate with the closed ends 237, 239, 241 and 243 of the spacer plates 55, 55', 57 and 57', respectively, to direct llow of the three fluids from one set of heat exchange plates identified by a Roman numeral to the adjacent set of heat exchange plates identified by another Roman numeral.

The heat exchange plates 17 and gaskets 103 are similar in construction to the plates and gaskets of FIG. 1 and are ported in a manner similar to that described abotve in connection with the description of the heat exchange assembly of FIG. 1 to permit llow through the channels defined between the heat exchange plates to and from the vertical iiow zones defined by the ports of the nested gaskets and plates. The gaskets and plates are ported in the same manner as described above in connection with the description of the arrangement of plates 17 and gaskets 103 of the heat exchange assembly of FIG. 2 and strips 150 are also employed.

A gasket is located immediately adjacent and beneath the top plate 51 as are similar gaskets to prevent leakage between heat exchange plates and the spacer plates and top and bottom plates.

The same arrangement of heat exchange plates is maintained in the group of plates identified by the Roman numeral X (FIG. 14) for flow of the brine and saltwater in heat exchange relation as above described in connection with the group X of the flow .ararngement of FIG. l1.

As appears in FIG. 14, the heat exchange plates, identified by the Roman numeral XI between the spacer plate 232 and the bottom plate 49, and the sets of heat exchange plates identified by the Roman numerals I-X between the spacer plate 220 and spacer plate 232 have a three fluid flow pattern in which the salt water flows in heat exchange relationship with brine and fresh water through three of the flow paths. The sea water, however, flows in heat exchange relation only with the brine in the first flow channel 250 of each of the sets of ilow channels identified by the Roman numerals I-X. 'Ihe same arrangement of ilow channels is maintained in each of the other sets of tlow channels identified by the Roman numerals II-IX as clearly appears in FIG. 14.

In the arrangement of FIG. l2 the aligning bars 63, 68 and 69 are not employed in the plate support assembly. substituted for these bars are a plurality of peripherally arranged U-shaped lchannel members 252. The vertically disposed guide channels 252 are each provided with a radially extending foot flange 254. The foot flanges 254 are alternated and some of these flanges are bolted as by bolts 255 to the botom plate 49 whereas other flanges are bolted, as by bolts 255, to the top plate 51. Opposite cach of the plurality of flanges 254, the top plate or bottom plate carries a rectangular bar 256 which is secured, as by bolts 258, to either of the plates 51 or 49 and this bar 256 has a surface bearing against the channel 252 to hold it in alignment and to prevent buckling thereof during compression of the plates by threading of the nuts 61 and 61 during assembly of the heat exchange assembly. The channels 252 perform the same .aligning and guiding function of the bars 63, 68 and 69 of the embodiment appearing in FIG. 2.

It will be noted -that the brine inlet 23 and sea water outlet 21 are both positioned on one side at the top of the heat exchange assembly and the sea water inlet 33a is located in the opposite side at the top of the heat exchange assembly whereas the sea water outlet, brine outlet and fresh water outlet are located at the bottom of the assembly. This arrangement is similar in this regard to the arrangement of the heat exchange assembly appearing in FIG. 11.

The support assembly appearing in FIG. 2 may be employed for a heat exchange arrangement in which a fluid is to be cooled by only one other fluid, i.e., an arrangement in which the sea water is to be cooled by flowing in counter-current relation only to fresh water and not by fresh water and sea water, or, as appears in FIG. 15, the support assembly of FIG. 12 including the channels 252 and the spacer plates may be employed in a two tluid flow system wherein the fluids tlow in countercurrent flow relation.

The spacer plates are identied by the numerals 260-267 in FIG. 15, and wider rectangular bars 257 are employed with the guide channels 252 in place of the guide bars 256. Bolts 258 secure the bars 257 to either of the plates 51 or 49.

As appears in FIGS. 15, 16 and 18, the coolant, brine, is introduced at the top of the assembly through an inlet 270 which communicates with a manifold 272 and flows through a labyrinth reversing flow pattern or path through the plurality of vertical flow zones and flow channels defined by the plurality of stacked heat exchange plates, gaskets and spacer plates to a manifold 274 which discharges from the heat exchanger through an outlet 276 located adjacent the bottom plate 49 of the assembly.

The sea water to be cooled by the brine flows through an inlet 278 located adjacent the bottom plate 49 of the assembly and into a manifold 281 which supplies the sea water to a labyrinth reversing ilow path defined by the plurality of flow zones, and channels defined by the stacked heat exchange plates, gaskets and spacer plates to an outlet manifold 282 located adjacent and carried by the top plate 51 which discharges from the assembly to an outlet 234. The brine and sea water llow in counter-current relation to each other through their respective iiow paths in the assembly.

The spacer plates are ported at one end only and the even numbered spacer plates are stacked alternately with respect to the odd numbered spacer plates so that the ported ends of the odd numbered plates are adjacent the unported plates of the even numbered plates. The spacer 

1. A PLATE SUPPORT ASSEMBLY FOR STACKABLE HEAT EXCHANGE PLATES INCLUDING A BOTTOM SUPPORT PLATE, A TOP SUBPORT PLATE, SPACER PLATES HAVING INLET AND OUTLET FLUID FLOW PORTS AND DISPOSED BETWEEN SAID SUPPORT PLATES FOR SPACING HEAT EXCHANGE PLATES POSITIONED BETWEEN SAID SUPPORT PLATES AND SAID SPACER PLATES, MEANS EXTENDING BETWEEN SAID SUPPORT PLATES FOR ALIGNING AND STRENGTHENING SAID ASSEMBLY, SAID ALIGNING AND STRENGTHENING MEANS INCLUDING A PLURALITY OF PERIPHERALLY SPACED AND VERTICALLY EXTENDING ASSEMBLY RODS CONNECTING SAID SUPPORT PLATES AND FURTHER INCLUDING A PLURALITY OF PERIPHERALLY SPACED BARS CARRIED BY SAID SUPPORT PLATES, SAID PLURALITY OF BARS INCLUDING FIRST BARS CARRIED BY THE BOTTOM SUPPORT PLATE AND SECOND BARS CARRIED BY THE TOP SUPPORT PLATE IN AXIAL ALIGNMENT WITH SAID FIRST BARS, SAID BARS ENGAGING EDGE SURFACES OF SAID HEAT EXCHANGE PLATES TO ALIGN SAID HEAT EXCHANGE PLATES IN SAID ASSEMBLY, THE FLUID FLOW PORTS FORMED IN SAID SPACER PLATES COOPERATING WITH FLUID FLOW PORTS FORMED IN SAID HEAT EXCHANGE PLATES TO DEFINE FLUID FLOW PATHS THEREBETWEEN THEREBY TO COMPLETE FORMATION OF AT LEAST ONE CONTINUOUS FLUID FLOW PATH THROUGH THE ASSEMBLY, AND MEANS FOR SEALING SAID PLATES AND SAID FLUID FLOW PATH AGAINST FLUID LEAKAGE. 